Crucial role of fluorine in fully alkylated ladder-type carbazole-based nonfullerene organic solar cells

Qiao He, Munazza Shahid, Xuechen Jiao, Eliot Gann, Flurin D. Eisner, Tingmang Wu, Zhuping Fei, Thomas D. Anthopoulos, Christopher R. McNeill, Martin Heeney

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Two fused ladder-type nonfullerene acceptors, DTCCIC and DTCCIC-4F, based on an electron-donating alkylated dithienocyclopentacarbazole core flanked by electron-withdrawing nonfluorinated or fluorinated 1,1-dicyanomethylene-3-indanone (IC or IC-4F), are prepared and utilized in organic solar cells (OSCs). The two new molecules reveal planar structures and strong aggregation behavior, and fluorination is shown to red-shift the optical band gap and downshift energy levels. OSCs based on DTCCIC-4F exhibit a power conversion efficiency of 12.6%, much higher than that of DTCCIC-based devices (6.2%). Microstructural studies reveal that while both acceptors are highly crystalline, bulk heterojunction blends based on the nonfluorinated DTCCIC result in overly coarse domains, while blends based on the fluorinated DTCCIC-4F exhibit a more optimal nanoscale morphology. These results highlight the importance of end group fluorination in controlling molecular aggregation and miscibility.

Original languageEnglish
Pages (from-to)9555-9562
Number of pages8
JournalACS Applied Materials & Interfaces
Volume12
Issue number8
DOIs
Publication statusPublished - 26 Feb 2020

Keywords

  • carbazole
  • fluorine effect
  • fully alkylated side chains
  • nonfullerene acceptors
  • organic solar cells

Cite this

He, Q., Shahid, M., Jiao, X., Gann, E., Eisner, F. D., Wu, T., Fei, Z., Anthopoulos, T. D., McNeill, C. R., & Heeney, M. (2020). Crucial role of fluorine in fully alkylated ladder-type carbazole-based nonfullerene organic solar cells. ACS Applied Materials & Interfaces, 12(8), 9555-9562. https://doi.org/10.1021/acsami.0c00981